Batching resource requests in a portable computing device

ABSTRACT

In a portable computing device having a node-based resource architecture, resource requests are batched or otherwise transactionized to help minimize inter-processing entity messaging or other messaging or provide other benefits. In a resource graph defining the architecture, each node or resource of the graph represents an encapsulation of functionality of one or more resources controlled by a processor or other processing entity, each edge represents a client request, and adjacent nodes of the graph represent resource dependencies. A single transaction of resource requests may be provided against two or more of the resources.

CROSS-REFERENCE TO RELATED APPLICATION

This is a continuation-in-part of U.S. patent application Ser. No.12/882,395, filed Sep. 15, 2010, entitled “SYSTEM AND METHOD FORMANAGING RESOURCES OF A PORTABLE COMPUTING DEVICE,” the specification ofwhich is incorporated herein in its entirety by this reference, and thebenefit of the filing date of which and of U.S. Provisional PatentApplication Ser. No. 61/530,748, filed Sep. 2, 2011, entitled “BATCHINGRESOURCE REQUESTS IN A PORTABLE COMPUTING DEVICE,” the specification ofwhich is also incorporated herein in its entirety by this reference, arehereby claimed.

DESCRIPTION OF THE RELATED ART

Portable computing devices (“PCDs”) are becoming increasingly popular.These devices may include cellular telephones, portable/personal digitalassistants (“PDAs”), portable game consoles, portable navigation units,palmtop computers, and other portable electronic devices. Each of thesedevices may have a primary function. For example, a cellular telephonegenerally has the primary function of receiving and transmittingtelephone calls.

In addition to the primary function of these devices, many includeperipheral functions. For example, a cellular telephone may include theprimary function of making cellular telephone calls as described above,and the peripheral functions of a still camera, a video camera, globalpositioning system (GPS) navigation, web browsing, sending and receivinge-mails, sending and receiving text messages, and push-to-talkcapabilities, etc. As the functionality of PCDs increases, the computingor processing power required to support such functionality alsoincreases. Processing power may be increased by increasing the number ofprocessors in the PCD. As the computing power and number of processorsincreases, there exists a greater need to effectively manage theprocessors.

Functions such as those described above may be embodied in variouscorresponding hardware and software elements that may be referred to asresources. A processor may request various resources at various timesunder control of software, such as an application program. In amulti-processor PCD, a first processor may control resources that aredifferent from the resources controlled by a second processor. However,it may be desirable for the first processor to be able to requestresources controlled by the second processor.

SUMMARY

A method and system for batching or otherwise transactionizing resourcerequests in a portable computing device having a plurality of resourcesmay help minimize inter-processor messaging or other messaging orprovide other benefits. In a portable computing device having anode-based software architecture, a resource may be included in a node.In an exemplary method, a plurality of nodes are instantiated. Theplurality of resources of the nodes may be defined by a directed acyclicgraph. Each node or resource of the graph represents an encapsulation offunctionality of one or more resources controlled by a processor orother processing entity. Each edge of the graph represents a clientrequest. Adjacent nodes of the graph represent resource dependencies. Inaccordance with the exemplary method, a single transaction of resourcerequests may be provided against two or more of the resources.

BRIEF DESCRIPTION OF THE DRAWINGS

In the figures, like reference numerals refer to like parts throughoutthe various views unless otherwise indicated. For reference numeralswith letter character designations such as “102A” or “102B”, the lettercharacter designations may differentiate two like parts or elementspresent in the same figure. Letter character designations for referencenumerals may be omitted when it is intended that a reference numeral toencompass all parts having the same reference numeral in all figures.

FIG. 1 is a functional block diagram illustrating exemplary elements ofa system for distributed resource management in a portable computingdevice (“PCD”);

FIG. 2 is a functional block diagram illustrating an example of aninstance in which a first processor needs to request a resourcecontrolled by a second processor;

FIG. 3 is a diagram of a first aspect of a node architecture thatmanages resources of a PCD;

FIG. 4 is a directed acyclic resource graph for a group of exemplaryresources of a PCD;

FIG. 5 is a general diagram of a second aspect of the node architecturethat manages resources of a PCD;

FIG. 6 is specific diagram of a second aspect of the node architecturethat manages resources of a PCD;

FIG. 7 is a flowchart illustrating a method for creating a nodearchitecture for managing resources of a PCD;

FIG. 8 is a continuation flowchart of FIG. 7 illustrating a method forcreating a node architecture for managing resources of a PCD;

FIG. 9 is a flowchart illustrating a sub-method or a routine of FIGS.7-8 for receiving node structure data in a software architecture for aPCD;

FIG. 10 is a flowchart illustrating a sub-method or a routine of FIGS.7-8 for creating a node in a software architecture for a PCD;

FIG. 11 is a flowchart illustrating a sub-method or a routine of FIG. 10for creating a client in a software architecture of a PCD;

FIG. 12 is a flowchart illustrating a method for creating a clientrequest against a resource in a software architecture for a PCD;

FIG. 13 illustrates a communication path between two processors, eachcontrolling resources of its own resource graph;

FIG. 14 is another flowchart illustrating a method for creating a nodearchitecture for managing resources of a PCD, where some of theresources are distributed resources;

FIG. 15 is another flowchart illustrating a method for creating a clientrequest against a distributed resource in a software architecture for aPCD;

FIG. 16 is a flowchart illustrating a method for handling a state queryagainst a non-proxied distributed resource in a software architecturefor a PCD;

FIG. 17A is a flowchart illustrating a first portion of a method forhandling a state query against a non-proxied distributed resource in asoftware architecture for a PCD;

FIG. 17B is a flowchart illustrating a second portion of a method forhandling a state query against a non-proxied distributed resource in asoftware architecture for a PCD.

FIG. 18 is a flowchart illustrating a method for batching ortransactionizing a plurality of resource requests.

FIG. 19 is an exemplary resource graph, in which the graph topologyprecludes a deadlock condition.

FIG. 20 is another exemplary resource graph, in which the graph topologydoes not preclude a deadlock condition.

FIG. 21 is an exemplary event timeline illustrating an instance in whicha deadlock occurs.

FIG. 22 is another exemplary event timeline illustrating an instance inwhich a pessimistic locking method prevents a deadlock.

FIG. 23 is a flowchart illustrating a method for a resource to handle aresource request that may be part of a transaction of resource requests.

DETAILED DESCRIPTION

The word “exemplary” is used herein to mean “serving as an example,instance, or illustration.” Any aspect described herein as “exemplary”is not necessarily to be construed as preferred or advantageous overother aspects.

In this description, the term “application” may also include fileshaving executable content, such as: object code, scripts, byte code,markup language files, and patches. In addition, an “application”referred to herein, may also include files that are not executable innature, such as documents that may need to be opened or other data filesthat need to be accessed.

The term “content” may also include files having executable content,such as: object code, scripts, byte code, markup language files, andpatches. In addition, “content” referred to herein, may also includefiles that are not executable in nature, such as documents that may needto be opened or other data files that need to be accessed.

As used in this description, the terms “component,” “database,”“module,” “system,” and the like are intended to refer to acomputer-related entity, either hardware, firmware, a combination ofhardware and software, software, or software in execution. For example,a component may be, but is not limited to being, a process running on aprocessor, a processor, an object, an executable, a thread of execution,a program, and/or a computer. By way of illustration, both anapplication running on a computing device and the computing device maybe a component. One or more components may reside within a processand/or thread of execution, and a component may be localized on onecomputer and/or distributed between two or more computers. In addition,these components may execute from various computer readable media havingvarious data structures stored thereon. The components may communicateby way of local and/or remote processes such as in accordance with asignal having one or more data packets (e.g., data from one componentinteracting with another component in a local system, distributedsystem, and/or across a network such as the Internet with other systemsby way of the signal).

In this description, the terms “communication device,” “wirelessdevice,” “wireless telephone,” “wireless communication device,” and“wireless handset” are used interchangeably. With the advent of thirdgeneration (“3G”) and fourth generation (“4G”) wireless technology,greater bandwidth availability has enabled more portable computingdevices with a greater variety of wireless capabilities.

In this description, the term “portable computing device” (“PCD”) isused to describe any device operating on a limited capacity powersupply, such as a battery. Although battery operated PCDs have been inuse for decades, technological advances in rechargeable batteriescoupled with the advent of third generation (“3G”) and fourth generation(“4G”) wireless technology, have enabled numerous PCDs with multiplecapabilities. Therefore, a PCD may be a cellular telephone, a satellitetelephone, a pager, a personal digital assistant (“PDA”), a smartphone,a navigation device, a smartbook or reader, a media player, acombination of the aforementioned devices, and a laptop computer with awireless connection, among others.

FIG. 1 is a functional block diagram of an exemplary, non-limitingaspect of a PCD 100 in the form of a wireless telephone for implementingmethods and systems for distributed resource management in a portablecomputing device. As shown, the PCD 100 includes an on-chip system 102that has a multi-core, central processing unit (“CPU”) 110A, a graphicsprocessor 110B, and an analog signal processor 126. These processors110A, 110B, 126 may be coupled together on one or more system busses oranother interconnect architecture, as known to one of ordinary skill inthe art.

The CPU 110A may comprise a zeroth core 222, a first core 224, etc.,through an Nth core 226, as understood by one of ordinary skill in theart. In alternative embodiments, instead of CPU 110A and a graphicsprocessor 110B, one or more digital signal processors (“DSPs”) may alsobe employed as understood by one of ordinary skill in the art. Further,in alternative embodiments, two or more multi-core processors may beincluded.

As illustrated in FIG. 1, a display controller 128 and a touchscreencontroller 130 are coupled to the multi-core CPU 110A. A touchscreendisplay 132 external to the on-chip system 102 is coupled to the displaycontroller 128 and the touchscreen controller 130. Also included in PCD100 is a video coder/decoder (“codec”) 134, e.g., a phase-alternatingline (“PAL”) encoder, a sequential couleur avec memoire (“SECAM”)encoder, a national television system(s) committee (“NTSC”) encoder orany other type of video encoder 134 coupled to the multi-core centralprocessing unit (“CPU”) 110A. A video amplifier 136 is coupled to thevideo encoder 134 and the touchscreen display 132. A video port 138 iscoupled to the video amplifier 136. As depicted in FIG. 2, a universalserial bus (“USB”) controller 140 is coupled to the CPU 110A. Also, aUSB port 142 is coupled to the USB controller 140. A subscriber identitymodule (SIM) card 146 may also be coupled to the CPU 110A. Further, asshown in FIG. 1, a digital camera 148 may be coupled to the CPU 110A. Inan exemplary aspect, the digital camera 148 is a charge-coupled device(“CCD”) camera or a complementary metal-oxide semiconductor (“CMOS”)camera.

As further illustrated in FIG. 1, a stereo audio CODEC 150 may becoupled to the analog signal processor 126. Moreover, an audio amplifier152 may be coupled to the stereo audio CODEC 150. In an exemplaryaspect, a first stereo speaker 154 and a second stereo speaker 156 arecoupled to the audio amplifier 152. FIG. 1 shows that a microphoneamplifier 158 may be also coupled to the stereo audio CODEC 150.Additionally, a microphone 160 may be coupled to the microphoneamplifier 158. In a particular aspect, a frequency modulation (“FM”)radio tuner 162 may be coupled to the stereo audio CODEC 150. Also, anFM antenna 164 is coupled to the FM radio tuner 162. Further, stereoheadphones 166 may be coupled to the stereo audio CODEC 150.

FIG. 1 further indicates that a radio frequency (“RF”) transceiver 168may be coupled to the analog signal processor 126. An RF switch 170 maybe coupled to the RF transceiver 168 and an RF antenna 172. As shown inFIG. 1, a keypad 174 may be coupled to the analog signal processor 126.Also, a mono headset with a microphone 176 may be coupled to the analogsignal processor 126. Further, a vibrator device 178 may be coupled tothe analog signal processor 126. FIG. 1 also shows that a power supply180, for example a battery, is coupled to the on-chip system 102. In aparticular aspect, the power supply 180 includes a rechargeable batteryor a direct current (“DC”) power supply that is derived from analternating current (“AC”)-to-DC transformer that is connected to an ACpower source.

Some of the above-described elements of the PCD 100 may comprisehardware, while others may comprise software, and still others maycomprise a combination of hardware and software. The term “resource” isused herein to refer to any such element, whether hardware, software ora combination thereof, that is controllable by a processor. A resourcemay be defined in one aspect as an encapsulation of the functionality ofsuch an element. Except where it may otherwise be indicated, the term“processor” is used herein to refer to a processor such as the CPU 110,graphics processor 110B, the analog signal processor 126, or to anyother processor, controller or similar element that operates under thecontrol of software, firmware, or similar control logic. A reference totwo or more “processing entities” includes processors on differentchips, different processing cores of the same processor chip, threads ofexecution on the same core, or any other processing entities betweenwhich there may be a data transport penalty or inefficiency.

As described in further detail below, an example of a resource is asoftware element that executes on a processor. A thread of execution ona processor, such as, for example, a thread relating to an executingapplication program, may access a resource by causing a “request” to beissued on the resource. As described below, resource requests areprocessed through a software-based system referred to in this disclosureas a “framework.” The term “client” is used broadly in this disclosureto refer to an element that effects the function of requesting aresource. Thus, as the terms are used herein, a thread may create ormake use of a client for the purpose of issuing resource requests. Itshould be noted that, in some instances, a resource may create or use aclient, such that a resource may cause a resource request to be issuedagainst another resource. As described in further detail below, suchother resource may be referred to herein as a “dependent” resource dueto a dependency relationship between the requesting resource andrequested resource. Resources and clients may be represented by datastructures in memory.

Since resources are controlled by specific processors in amulti-processor PCD 100, not every processor in PCD 100 has access toevery resource in PCD 100. FIG. 2 illustrates an example of an instancein which it may be desirable for a first processor 202 in PCD 100 toissue a resource request 203 against a resource 204 controlled by asecond processor 206 in PCD 100. Note that the first processor 202 mayalso control a plurality of resources 205. Likewise, the secondprocessor 206 may control a plurality of additional resources 207.

In an instance in which the first processor 202 is executing a thread208 relating to, for example, a video player application program, thethread 208 may call for adjustment of one or more operating parametersof the first processor 202 that enhance the performance of the firstprocessor 202. (Although thread 208 and resource 204 are conceptuallyillustrated as residing in their respective processors 202 and 206 forpurposes of clarity, one of ordinary skill in the art understands thatsuch elements are executed or otherwise operated upon by the processorin the processor's memory space in accordance with well understoodcomputing principles.) Such operating parameters may include, forexample, clock speed and bus speed. For example, various processors mayuse the same bus clock, but only one of the processors may have direct(hardware-level) control of the bus clock. Increasing clock speed mayresult in better performance by, for example, a video player applicationprogram, since the playback of video is generally a more processingpower-intensive task than some other tasks. As processing power iscommonly expressed in millions of instructions per second (“MIPS”), thethread 208 may issue a call for a certain number of MIPS. The powermanager resource 204 may include an algorithm that, in response to arequest for a specified number of MIPS, causes changes in signals 210that may represent clock speed, bus speed or other parameters thatpromote the first processor 202 operating at the requested MIPS level.

It may be possible for a thread to access the power manager resource 204through an application program interface (API) specific to a bus orprotocol through which the first processor 202 may communicate with thesecond processor 206. However, the framework described below may providea more uniform way to handle resource requests than a resource-specificand bus-specific API. As described below, via the framework, resourcerequests are issued and serviced in a uniform manner without regard towhether the request is against a resource controlled by the sameprocessor from which the resource request is issued or against aresource controlled by a different processor. A resource controlled bythe same processor from which the resource request is issued may bereferred to as a “native” resource. A resource controlled by a processorother than that from which the resource request is issued may bereferred to herein as a “remote resource” or “distributed resource.”

In addition, issuing a request against a remote resource incursprocessing overhead in the form of a time delay or latency. That is, acertain amount of time is required for the message or messages relatingto the resource request to be sent between processors. In someinstances, a single resource request may result in multipleinter-processor messages. The resource request batching featuredescribed in this specification may help minimize the number ofinter-processor messages in some instances.

FIG. 3 is a diagram comprising functional blocks which representsoftware or hardware (or both) of the PCD 100. The blocks to the left ofthe line “A” represent resources of the PCD 100 that are controlled bythe CPU 110A. Such resources may include: the CPU 110A itself, alsoreferred to generally as the first hardware element (hardware element#1); a clock 442 for the CPU 110A, also referred to generally as thesecond hardware element (hardware element #2); a bus arbiter orscheduler 422, also referred to generally as the third hardware element(hardware element #3); a bus program A—444A, also referred to generallyas the first software element (software element #1); a bus programB—444B, also referred to generally as the second software element(software element #2); a clock program AHB, referred to generally as thethird software element (software element #3); and an action or functionmonitored by a software element generally indicated as a keypress 448.The CPU 110A controls or has access to the above-referenced resourcesbecause the resources are within the memory space of the CPU 110A and noother restrictions, such as security restrictions, exist that wouldinhibit CPU 110A from accessing those resources. For example, CPU 110Amay be capable of controlling or accessing hardware registers of thoseresources. It should be noted that PCD 100 may include other CPUs 110(see, e.g., FIG. 2) that control or have access to resources other thanthe above-referenced resources.

A framework manager 440, which may comprise a library of computerinstructions, manages nodes that encapsulate functionality of theresources. That is, the nodes may be accessed to indirectly access theresources. For convenience, a node encapsulating the functionality of aresource may be referred to herein as including, comprising, having,etc., the resource. Each node may include one or more resources. Thenodes may be defined in software code, firmware, or a similar medium,and instantiated as data structures in, for example, memory 112 (FIG. 1)during operation of the PCD 100. The nodes 601 may be instantiatedduring a start-up, power-up, initialization, boot-up, etc., sequence, orat any other suitable time during operation of the PCD 100. It should benoted that a reference herein to instantiating, issuing a request on, orotherwise interacting with a resource should be understood as meaninginteracting with a node that includes that resource. For the remainderof this disclosure, a generic or non-specific node will be designatedwith reference numeral 601 as described below with reference to FIG. 5.

Nodes 601 may include, for example, a first node 602 having a singleresource that generally corresponds with the first hardware element orcentral processing unit 110. With the software architecture described inthis disclosure, each resource of a node 601 may be provided with aunique name comprising one or more alphanumeric characters. In theexemplary embodiment illustrated in FIG. 3, the resource of the firstnode 602 has been assigned the resource name of “/core/cpu.” Thisexemplary resource name generally corresponds to conventional filenaming structures known to one of ordinary skill in the art. However, asrecognized by one of ordinary skill the art, other types of resourcenames containing any other combination of alpha-numeric charactersand/or symbols are well within the scope of this disclosure.

Nodes 601 may further include, for example, a second node 622 having aplurality of resources. In this exemplary embodiment, the second node622 has a first resource comprising a single hardware elementcorresponding to the bus arbiter or scheduler 422. The second resourceof the second node 622 comprises a software element generallycorresponding to the first software element of the bus program A 444A.The third resource of the second node 622 comprises another softwareelement generally corresponding to the second software element of thebus program B 444B. One of ordinary skill in the art recognizes that anycombination and any number of resources and resource types for a givennode 601 are well within the scope of this disclosure.

FIG. 3 also illustrates a first client 648 that generally corresponds toan action or function of the two software elements 448, 450. In theexemplary embodiment illustrated in FIG. 3, the first client 648generally corresponds to a keypress action that may occur within aparticular application program module 105 supported by the portablecomputing device 100. However, one of ordinary skill in the artrecognizes that other actions and/or functions of software elementsbesides keypresses are well within the scope of this disclosure. Furtherdetails about client requests 648 and their respective creation will bedescribed below in connection with FIG. 11.

FIG. 3 also illustrates relationships between particular architecturalelements. For example, FIG. 3 illustrates a relationship between theclient 648 and the first node 602. Specifically, the first client 648may generate a client request 675A, illustrated with dashed lines, whichis managed or handled by the first node 602 that comprises the resource“/core/cpu.” Typically, there are a predetermined or set number of typesof client requests 675. Client requests 675 will be described in furtherdetail below in connection with FIG. 11.

Other relationships displayed in FIG. 3 include dependencies illustratedwith dashed lines 680. Dependencies are relationships between respectiveresources of another node 601. A dependency relationship usuallyindicates that a first resource (A) is reliant upon a second resource(B) that may provide the first resource (A) with information orimplement some behavior. This information may be a result of anoperation performed by a second resource (B) or it may simply comprisestatus information that is needed by the first resource (A) or anycombination thereof. The first resource (A) and second resource (B) maybe part of the same node 601 or they may be part of different nodes 601.It should be noted that client requests 675 may originate not only fromthreads of execution, such as in the example of the above-describedkeypress action, but also from other nodes 601. To obtain information orbehavior from a dependent node 601, a node 601 may issue a clientrequest 675 to its dependent node 601. Thus, the dashed lines 680 thatindicate dependencies may also indicate the direction of potentialclient requests 675.

In FIG. 3, the first node 602 is dependent upon the second node 622 asindicated by the dependency arrow 680B which originates with the firstnode 602 and extends to the second at 622. FIG. 3 also illustrates thatthe first node 602 is also dependent upon the third node 642 asillustrated by the dependency arrow 680A. FIG. 3 also illustrates thatthe second node 622 is dependent upon the fourth node 646 as illustratedby the dependency arrow 680C. One of ordinary skill in the artrecognizes that the dependencies 680 illustrated with the dashed arrowsof FIG. 3 are only exemplary in nature and that other combinations ofdependencies between respective nodes 601 are within the scope of thisdisclosure.

The framework manager 440 is responsible for maintaining therelationships described above, that include, but are not limited to, theclient requests 675 and the dependencies 680 illustrated in FIG. 3. Somesuch relationships, such as dependencies, exist at a PCD start-up time(i.e., power-up, initialization, boot-up, etc.) by virtue of the way theresources and their nodes 601 have been defined in the software code inPCD 100 that the framework manager 440 accesses at such a start-up timeto begin the node instantiation process. Other such relationships, suchas client requests 675, arise after nodes 601 have been instantiated,such as during execution of an application program thread in which anapplication program invokes a resource. Whether client requests 675originate from executing application program threads or similar elementsother than nodes 601 (e.g., client request 675A) or originate from anode 601, client requests 675 are directed through the framework manager440. The framework manager 440 directs the transfer of information amongthe nodes 601. Conceptually, the framework manager 440 serves as amatrix through which multiple threads may essentially concurrentlycommunicate with the nodes 601. Though different threads may involvedifferent data, the same framework manager software code may servicemultiple threads.

As described below in further detail, the framework manager 440 mayinstantiate a node 601 as soon as the node's dependent nodes areinstantiated, i.e., when the dependencies 680 for any given node 601have been resolved. The framework manager 440 attempts to instantiateall nodes 601 that have been defined in the software architecture of PCD100. A dependency 680 is completed or resolved when a resource thatsupports a dependency is in existence or is in a ready state forhandling information that relates to the dependency 680.

For example, the first node 602 comprising the single resource“/core/cpu” may not be instantiated by the framework manager 440 if thethird node 642 comprising the single resource “/clk/cpu” has not beeninstantiated because of the dependency relationship 680A that existsbetween the first node 602 and the third node 642. Once the third node642 has been instantiated by the framework manager 440, then theframework manager 440 may instantiate the second node 602 because of thedependency relationship 680A.

If the framework manager 440 is unable to instantiate a particular node601 because one or more of its dependencies 680 are incomplete orunresolved, the framework manager 440 will continue running or executingsteps corresponding to those nodes 601 that were instantiatedsuccessfully. The framework manger 440 will usually skip over a call fora particular node 601 that may not exist due to incomplete dependenciesin which dependent resources have not been created, and return messagesto that call which reflect that incomplete status.

In a multi-core environment, such as illustrated in FIG. 1, theframework manager 440 may create or instantiate nodes 601 on separatecores, such as the 0th, first and Nth cores 222, 224, and 226 of FIG. 1.Nodes 601 may generally be created in a multi-core environment onseparate cores and in parallel as long as the nodes 601 are notdependent on one another and if all of a particular node's correspondingdependencies, as described below, are complete. In a multi-processorenvironment, the nodes 601 may be created or instantiated on variousprocessors, such as the CPU 110A, graphics processor 110B, etc., ofFIG. 1. That is, some nodes 601 may exist in the memory space of oneprocessor, while other nodes 601 may exist in the memory space ofanother processor. It should be noted, however, that nodes 601 on oneprocessor may not be accessible to nodes 601 on the other processor viaonly framework manager 440.

A remoting framework manager 300 that is similar to the above-described(main) framework manager 440 may exist in parallel with and as anextension to the framework manager 440. The remoting framework manager300 cooperates with or works with the framework manager 440 tocoordinate inter-processor information transfers between nodes 601 ondifferent processors. That is, the remoting framework manager 300 helpsframework manager 440 maintain the relationships described above, suchas dependencies and client requests, in instances in which the nodes 601that are involved exist on different processors. Thus, nodes 601 on oneprocessor may not rendered accessible to nodes 601 on another otherprocessor via the combined effect of framework managers 440 and 300.Moreover, the combination of framework managers 440 and 300 may performall of the functions ascribed in this disclosure to framework manager440, whether the nodes 601 that are involved exist on the same processordifferent processors. In such a multi-processor embodiment, individualcopies of the software that framework managers 300 and 440 comprise mayreside in the domain of each of the processors. Thus, each processor hasaccess to the same framework manager software.

FIG. 4 conveniently reorganizes the above-described nodes 602, 622, 642and 646 in the form of a directed acyclic graph (“DAG”) 400. The graph400 is another way of defining the software architecture describedabove. In the lexicon of graph theory, the vertices of the graph 400correspond to the nodes 601, the edges of the graph 400 correspond toclient requests 675, and adjacent nodes or vertices represent resourcedependencies. One of ordinary skill in the art will recognize that thegraph 400 is a directed graph as a result of the dependencies and isacyclic because the framework manager 440 prevents a cycle from beingdefined in which resource A depends on resource B and resource B dependson resource A. That is, the framework manager 440 will not instantiatetwo nodes 601 that are (erroneously) defined to depend on each other.The acyclic property of the graph is important to prevent deadlocks,since, as described below, each node 601 is locked (in a transactionprocessing sense) when it is accessed. If two nodes 601 were to dependon each other in an instance in which a first thread were to access andlock one of these two nodes 601 at the same time that a second threadwere to access and lock the other of these two nodes 601, both threadswould be hung. However, in the relatively rare instances in which asoftware developer or other such person involved in defining thesoftware architecture deems it desirable to define in the softwarearchitecture two resources that depend on each other, the two (or more)resources may be included in the same node 601 as each other. Tworesources in the same node will share the same lock state. It is atleast in part for this reason that a software developer or other suchperson may choose to define a plural-resource node such as node 622 inthe architecture.

Although this disclosure may, for purposes of clarity and convenience,reference a “node” 601 rather than a “resource” of the node 601, itshould be understood that client requests may be directed to specifiedresources rather than nodes. In other words, a node 601, which, asdescribed above, may be a data structure encapsulating of thefunctionality of one or more resources, may be transparent from theperspective of a client or other issuer of a client request such asanother node 601. From the perspective of a client, a request is issuedagainst a resource rather than a node. Likewise, from the perspective ofa client, a state query, event, or other element of the architecture isassociated with a resource rather than a node.

A resource graph such as the exemplary graph 400 is useful forunderstanding the instantiation of nodes 601 in accordance withdependencies, described below with regard to FIGS. 6-10. Leaf nodes,such as the nodes 642 and 646, are instantiated before non-leaf nodes,because leaf nodes have no dependencies. In general a node 601 must beinstantiated before a node that depends on it may be instantiated.Furthermore, it can be seen that servicing a resource requestcorresponds to traversing a directed acyclic graph in which the verticescorrespond to the nodes 601, the edges correspond to client requests675, and adjacent nodes or vertices represent resource dependencies.

In a multi-processor PCD 100, a first processor may have access to or becapable of controlling a first set of nodes 601 in a first resourcegraph, while a second processor may have access to or be capable ofcontrolling a second set of nodes 601 in a second resource graph, wherethe first and second resource graphs do not share any resources, i.e.,they are mutually exclusive resource graphs. That is, in such anenvironment, each processor has its own resource graph that definesrelationships among resources and other elements that are not accessibleto other processors. The distributed resource management of the presentdisclosure relates to maintaining the relationships described above,such as dependencies and client requests, in instances in which two ormore processors each have access to resources in their own resourcegraphs and do not have access to resources in other processors' resourcegraphs.

The above-referenced limitation upon access to resources may, in someembodiments, be limited by hardware configuration. That is, a processormay have no means by which it can affect a hardware device, such as aregister, because the hardware device is controlled by or in the memoryspace of another processor. Alternatively, or in addition, thelimitation upon access to resources may be imposed in software, forreasons such as minimizing exposure of a processor to security risks(e.g., a virus that may be infecting another processor).

FIG. 5 is a general diagram of another aspect of a software architecture500B1 for a system that manages resources of a PCD 100 of FIG. 1. Thisaspect is described for purposes of clarity in the context of a PCD 100and architecture in which all resources and other elements that areinvolved are controlled by the same processor, i.e., they are includedin the same resource graph. In this general diagram, the one or moreresources of each node 601 have not been provided with unique names. Thenode or resource graph 500B1 of FIG. 5 comprises only the nodes 601,clients 648, events 690, and query functions 695 supported by thearchitecture or framework manager 440. Each node 601 has beenillustrated with an oval shape and arrows 680 with specific directionswhich represent respective dependencies between resources within a node601.

FIG. 5 also illustrates how a client 648 of the first node 601A mayissue a client request 675 to the first node 601A. After these clientrequests 675 are issued, the second node 601B may trigger an event 690or provide a response to a query 695, in which messages corresponding tothe event 690 and the query 695 flow back to the client 648.

FIG. 6 is a more specific diagram of the above-described aspect of thesoftware architecture 500B2 for a system that manages resources of a PCD100 of FIG. 1. FIG. 6 illustrates a node or resource graph 500B2 thatcomprises only the nodes 601 with specific, yet exemplary resourcenames, as well as clients 648, events 690, and query functions 695corresponding to those of FIG. 3. Each node 601 has been illustratedwith an oval shape and arrows 680 with specific directions whichrepresent respective dependencies between resources within a node 601.

For example, the first node 602 has a dependency arrow 680B to indicatethat the first node 602 is dependent upon the three resources of thesecond node 622. Similarly, the third resource “/bus/ahb/sysB/”comprising the second software element 444B and generally designatedwith the reference letter “C” in FIG. 11C has a dependency arrow 680Cthat indicates this third resource (C) is dependent upon the single“/clk/sys/ahb” resource of the fourth node 646.

FIG. 6 also illustrates the output data from nodes 601 which maycomprise one or more events 690 or query functions 695. A query function695 is similar to an event 690. The query function 695 may have a queryhandle that may or may not be unique. The query function is generallynot externally identified and generally it does not have a state. Thequery function 695 may be used to determine the state of a particularresource of a node 601. The query function 695 and the events 690 mayhave relationships with an established client 648 and theserelationships are represented by directional arrows 697 to indicate thatinformation from respective event 690 and query function 695 are passedto a particular client 648.

The node or resource graphs 500B of FIG. 5-6 represent relationshipswhich exist in memory under the control of a processor and which aremanaged by the framework manager 440. The node or resource graph 500Bmay be automatically generated by the framework manager 440 as a usefultool for identifying relationships between respective elements managedby the framework manager 440 and for troubleshooting by a software team.

FIG. 7 is a flowchart illustrating a method 1000A for creating orinstantiating software structures for managing resource(s) of a PCD 100.This method is described for purposes of clarity in the context of anarchitecture in which all resources and other elements that are involvedare controlled by the same processor, i.e., they are included in thesame resource graph. Block 1005 is the first routine of the method orprocess 1000 for managing resources of a PCD 100. In block 1005, aroutine may be executed or run by the framework manager 440 forreceiving node structure data. The node structure data may comprise adependency array that outlines the dependencies a particular node 601may have with other nodes 601. Further details about node structure dataand this routine or submethod 705 will be described in more detail belowin connection with FIG. 9.

Next, in block 1010, the framework manager 440 may review the dependencydata that is part of the node structure data received in block 1005. Indecision block 1015, the framework manager 440 may determine if the nodestructure data defines a leaf node 601. A leaf node 601 generally meansthat the node to be created based on the node structure data does nothave any dependencies, such as the nodes 642 and 646 in FIGS. 3-4. Ifthe inquiry to decision block 1015 is positive, meaning that the nodestructure data for creating the current node does not have anydependencies, then the framework manager 440 continues to routine block1025.

If the inquiry to decision block 1015 is negative, then the “No” branchis followed to decision block 1020 in which the framework managerdetermines if all of the hard dependencies within the node structuredata exist. A hard dependency may comprise one in which a resourcecannot exist without it. Meanwhile, a soft dependency may comprise onein which a resource may use the dependent resource as an optional step.A soft dependency means that a node 601 or resource of the node 601which has a soft dependency may be created or instantiated within thenode architecture even when the soft dependency does not exist.

An example of a soft dependency may comprise an optimization featurethat is not critical to the operation for a resource oriented node 601containing multiple resources. The framework manager 440 may create orinstantiate a node or a resource for all hard dependencies that arepresent even when a soft is dependency is not present for those nodes orresources which have soft dependencies that are not created. A call backfeature may be used to reference the soft dependency so that when thesoft dependency becomes available to the framework manager 440, theframework manager 440 will inform each callback referencing the softdependency that the soft dependencies are now available.

If the inquiry to decision block 1020 is negative, then the “No” branchis followed to block 1027 in which the node structure data is stored bythe framework manager 440 in temporary storage such as memory and theframework manager 440 creates a call back feature associated with thisun-instantiated node.

If the inquiry to decision block 1015 is positive, then the “Yes” branchis followed to routine 1025 in which a node 601 is created orinstantiated based on the node structure data received in routine block1005. Further details of routine block 1025 will be described below inconnection with FIG. 9. Next, in block 1030, the framework manager 440publishes the newly created node 601 using its unique resource name(s)so that other nodes 601 may send information to or receive informationfrom the newly created node 601.

Referring now to FIG. 8, which is a continuation flow chart of FIG. 7,in block 1035, the framework manager 440 notifies other nodes 601 whichare dependent on the newly created node 601 that the newly created node601 has been instantiated and is ready to receive or transmitinformation. According to one exemplary aspect, notifications aretriggered immediately when a dependent node, like node 601B of FIG. 5,is created, i.e., the notifications are performed recursively. So ifnode 601B of FIG. 5 is constructed, node 601A is immediately notified.This notification may allow node 601A to be constructed (since node 601Bwas node 601A's final dependency). Construction of node 601B may causesother nodes 601 to be notified, and so on. Node 601B does not getcompleted until the final resource dependent on node 601B is completed.

A second, slightly more complex, implementation is to put all of thenotifications onto a separate notification queue, and then run throughthe queue beginning at a single point in time, i.e., the notificationsare performed iteratively. So when node 601B of FIG. 5 is constructed,the notification to node 601A is pushed onto a list. Then that list isexecuted and node 601A is notified. This causes the notification toother additional nodes 601 (besides node 601A, not illustrated in FIG.5) to be put on the same list, and that notification is then sent afterthe notification to node 601A is sent. The notifications to other nodes601 (besides the notification to node 601A) does not occur until afterall the work associated with node 601B and node 601A has been completed.

Logically, these two implementations are equivalent, but they havedifferent memory consumption properties when implemented. The recursiverealization is simple but can consume an arbitrary amount of stackspace, with the stack consumption being a function of the depth of thedependency graph. The iterative implementation is slightly more complexand requires a bit more static memory (the notification list), but stackusage is constant irrespective of the depth of a dependency graph, suchas illustrated in FIG. 5.

Also, notification of node creation in block 1035 is not limited toother nodes. It may also used internally for alias construction. Anyarbitrary element in the system 500A may use the same mechanism torequest for notification when a node becomes available, not just othernodes. Both nodes and non-nodes may use the same notification mechanism.

In decision block 1040, the framework manager 440 determines if othernodes 601 or soft dependencies are now released for creation orinstantiation based on the creation of the current node 601. Decisionblock 1040 generally determines whether resources may be created becausecertain dependency relationships 680 have been fulfilled by the currentnode which has recently undergone creation or instantiation.

If the inquiry to decision block 1040 is positive, then the “Yes” branchis followed back to routine block 1025 in which the released node 601may now be created or instantiated because of the fulfillment of adependency by the node 601 that was just created.

If the inquiry to decision block 1040 is negative, then the “No” branchis followed to block 1045 in which the frame work manager 440 may managecommunications between elements of the software architecture asillustrated in FIG. 2. Next, in block 1050, the framework manager 440may continue to log or record actions taken by resources by using theresource names associated with a particular resource. Block 1045 may beexecuted by the framework manager 440 after any action taken by theframework manager 440 or any of the elements managed by the frameworkmanager 440, such as the resources, nodes 601, clients 648, events 695,and query functions 697. Block 1045 shows another aspect of the nodearchitecture in which the framework manager 440 may maintain a runninglog of activity that lists actions performed by each element accordingto their unique identifier or name provided by the authors who created aparticular element, such as a resource of a node 601.

Compared to the prior art, this logging of activity in block 1050 thatlists unique names assigned to each resource of a system is unique andmay provide significant advantages such as used in debugging and errortroubleshooting. Another unique aspect of the node architecture 500A isthat separate teams may work on different hardware and/or softwareelements independently of one another in which each team will be able touse resource names that are unique and easy to track without the needfor creating tables to translate less meaningful and usually confusingresource names assigned by other teams and/or the original equipmentmanufacturer (OEM).

Next, in decision block 1055, the framework manager 440 determines if alog of activity recorded by the framework manager 440 has beenrequested. If the inquiry to decision block 1055 is negative, then the“No” branch is followed to the end of the process in which the processreturns back to routine 1005. If the inquiry to decision block 1055 ispositive, then the “Yes” branch is followed to block 1060 in which theframework manager 440 sends the activity log comprising meaningfulresource names and respective actions performed by the resource names toan output device, such as a printer or a display screen and/or both. Theprocess then returns to routine block 1005 described above.

FIG. 9 is a flowchart illustrating a sub-method or a routine 1005 ofFIG. 7 for receiving node structure data that defines a softwarearchitecture of a PCD 100. The receiving method may occur at anysuitable time, such as, for example, when the PCD 100 is started up orinitialized. In such an instance, the node structure data is receivedwhen a processor reads the corresponding software code from memory inpreparation for instantiating the nodes 601 in accordance with thearchitecture. Block 1105 is the first step in the sub method or routine1005 of FIG. 7. In block 1105, the framework manager 440 may receive aunique name for a software or hardware element, such as the CPU 110 andthe clock 442 of FIG. 7. As discussed previously, a node 601 mustreference at least one resource. Each resource has a unique name in thesystem 500A. Each element within the system 500A may be identified witha unique name. Each element has a unique name from a characterperspective. In other words, generally, there are no two elements withinthe system 500A which have the same name. According to exemplary aspectsof the system, resources of nodes 601 may generally have unique namesacross the system, but it is not required that client or event names beunique, though they may be unique as desired.

For convenience, a conventional tree file naming structure or filenaming “metaphor” that employs forward slash “/” characters for creatingunique names may be employed, such as, but not limited to, “/core/cpu”for CPU 110 and “/clk/cpu” for clock 442. However, as recognized by oneof ordinary skill the art, other types of resource names containing anyother combination of alphanumeric characters and/or symbols are wellwithin the scope of this disclosure.

Next, in block 1110, the framework manager 440 may receive data for oneor more driver functions associated with one or more resources of thenode 601 being created. A driver function generally comprises the actionto be completed by one or more resources for a particular node 601. Forexample, in FIGS. 7A-7B, the driver function for the resource /core/cpuof node 602 may request the amount of bus bandwidth and the CPU clockfrequency it requires in order to provide the requested amount ofprocessing that has been requested. These requests would be made viaclients of the resources in nodes 642 and node 622. The driver functionfor /clk/cpu in node 642 would usually be responsible for actuallysetting the physical clock frequency in accordance with the request itreceived from the /core/cpu resource of node 602.

In block 1115, the framework manager 440 may receive node attributedata. The node attribute data generally comprises data that defines thenode policies such as security (can the node be accessed via user spaceapplications), remotability (can the node be accessed from otherprocessors in the system) and accessibility (can the resource supportmultiple concurrent clients). The framework manager 440 may also defineattributes that allow a resource to override default framework behavior,such as request evaluation or logging policy.

Subsequently, in block 1120, the framework manager 440 may receivecustomized user data for the particular node 601 being created. The userdata may comprise a void “star” field as understood by one of ordinaryskill in the art with respect to the “C” programming language. User datais also known to one of ordinary skill in the art as a “trust me” field.Exemplary customized user data may include, but is not limited to,tables such as frequency tables, register maps, etc. The user datareceived in block 1120 is not referenced by the system 500A, but allowsfor customization of a resource if the customization is not recognizedor fully supported by the framework manager 440. This user datastructure is a base class in the “C” programming language intended to beextended for particular or specific uses.

One of ordinary skill the art recognizes that other kinds of datastructures for extending specific uses of a particular class are withinthe scope of this disclosure. For example, in the programming languageof “C++” (C-plus-plus), an equivalent structure may comprise the keyword “public” which would become an extension mechanism for a resourcewithin a node 601.

Next, in block 1125, the framework manager 440 may receive dependencyarray data. The dependency array data may comprise the unique andspecific names of one or more resources 601 on which the node 601 beingcreated is dependent. For example, if the first node 602 of FIG. 6 wasbeing created, then in this block 1125, the dependency array data maycomprise the resource names of the three resources of the second node622 and the single resource name of the third node 642 on which thefirst node 602 is dependent.

Subsequently, in block 1130, the framework manager 440 may receiveresource array data. The resource array data may comprise parameters forthe current node being created, such as parameters relevant to the firstnode 602 of FIGS. 7B-7C if this first node 602 was being created. Theresource array data may comprise one or more of the following data: thenames of other resources; unit; maximum value; resource attributes;plug-in data; and any customized resource data similar to the customizeuser data of block 1120. The plug-in data generally identifies functionsretrieved from a software library and usually lists the client typesthat may be supported by the particular node or plurality of nodes beingcreated. The plug-in data also allows for customization of clientcreation and destruction. After block 1130, the process returns to block1010 of FIG. 7.

In FIG. 9, the attribute data block 1115, customized user data block1120, and the dependency array data block 1125 have been illustratedwith dashed lines to indicate that these particular steps are optionaland not required for any given node 601. Meanwhile, the unique nameblock 1105, a driver function block 1110, and resource array data block1130 have been illustrated with solid lines to indicate that these stepsof routine 1005 are generally important for creating a node 601.

FIG. 10 is a flowchart illustrating a sub-method or a routine 1025 ofFIG. 7 for creating a node in a software architecture for a PCD 100.Routine block 1205 is the first routine in the sub-method or routine1025 for instantiating or creating a node 601 according to one exemplaryembodiment. In routine block 1205, one or more clients 648 that areassociated with the node 601 being instantiated are created in thisstep. Further details about routine block 1205 will be described infurther detail below in connection with FIG. 11.

In block 1210, the framework manager may create or instantiate the oneor more resources corresponding to the node structure data of block 705.Next, in block 1215, the framework manager 440 may activate the driverfunctions received in routine block 1110 of routine block 1005.According to one exemplary aspect, the driver functions may be activatedusing the maximum values received in the resource array data block 1130of routine block 1005. According to another, preferred, exemplaryaspect, each driver function may be activated with an optional, initialvalue that is passed along with the node structure data from routine1005. If initial data is not provided, the driver function isinitialized at 0—the minimum value. The driver function is also usuallyactivated in manner such that it is known that it is being initialized.This enables the resource to perform any operations that are specific toinitialization, but do not need to be performed during normal or routineoperation. The process then returns to step 1030 of FIG. 7.

FIG. 11 is a flowchart illustrating a sub-method or a routine 1205 ofFIG. 10 for creating or instantiating a client 648 in a softwarearchitecture of a PCD 100. Block 1305 is the first step of routine block1205 in which a client 648 of one or more resources 601 is created. Inblock 1205, the framework manager 440 receives a name assigned to theclient 648 being created. Similar to resource names, the name for aclient 648 may comprise any type of alphanumeric and/or symbols.

Next, in block 1310, customized user data may be received by theframework manager 440 if there are any particular customizations forthis client 648 being created. Block 1310 has been illustrated withdashed lines to indicate that the step is optional. The customized userdata of block 1310 is similar to the customized user data discussedabove in connection with the creation of resources for nodes 601.

In block 1315, the framework manager 440 receives the client typecategory assigned to the particular client being created. The clienttype category as of this writing may comprise one of four types: (a)required, (b) impulse, (c) vector, and (d) isochronous. The client typecategory list may be expanded depending upon the resources being managedby the system 101 and upon the application programs relying upon theresources of the nodes 601.

The required category generally corresponds with the processing of ascalar value that is passed from the required client 648 to a particularresource 601. For example, a required request may comprise a certainnumber of millions of instructions per second (MIPs). Meanwhile, theimpulse category generally corresponds with the processing of a requestto complete some activity within a certain period of time without anydesignation of a start time or stop time.

An isochronous category generally corresponds with a request for anaction that is typically reoccurring and has a well-defined start timeand a well-defined end time. A vector category generally correspondswith an array of data that usually is part of multiple actions that arerequired in series or in parallel.

Subsequently, in block 1320, the framework manager 440 receives datathat indicates whether the client 648 has been designated as synchronousor asynchronous. A synchronous client 648 is one that typically requiresthe framework manager 440 to lock a resource of a node 601 until theresource 601 returns data and an indication that the resource 601 hasfinished completing the requested task from the synchronous client 648.

On the other hand, an asynchronous client 648 may be handled by one ormore threads in parallel which are accessed by the framework manager440. The framework 440 may create a callback to a thread and may returna value when the callback has been executed by a respective thread. Oneof ordinary skill the art recognizes that the asynchronous client 648does not lock up a resource like a synchronous client 648 does when thetask of the synchronous client 648 is being executed.

After block 1320, in decision block 1325, the framework manager 440determines if the resource identified by the client 645 are available.If the inquiry to decision block 1325 is negative, then the “No” branchis followed to block 1330 in which a null value or message is returnedto a user indicating that the client 648 cannot be created at this time.

If the inquiry to decision block 1325 is positive, then the “Yes” branchis followed to decision block 1335 in which the framework manager 440determines if each resource identified by the client 648 supports theclient type provided in block 1310. If the inquiry to decision block1335 is negative, then the “No” branch is followed back to block 1330 inwhich a null value or message is returned indicating that the client 648cannot be created at this time.

If the inquiry to decision block 1335 is positive, then the “Yes” branchis followed to block 1340 in which the framework manager 440 creates orinstantiates the client 648 in memory. Next, in block 1345, if anycustomized user data is received in block 1310, such as optionalarguments, then these optional arguments may be mapped with theirrespective resources to a particular node 601. Next, in block 1350, thenewly created client 645 is coupled to its corresponding one or moreresources in an idle state or on requested state as described above. Theprocess then returns to block 1210 of FIG. 10.

FIG. 12 is a flow chart illustrating a method 1400 for creating a clientrequest 675 against a resource 601 in a software architecture for a PCD100. The method 1400 is generally executed after client and nodecreation (instantiation) as described above in connection with FIGS.7-11.

Block 1405 is the first step in the method 1400 for creating a clientrequest 675 against the resource 601. This method 1400 will describe howthe following three types of client requests 675 are handled by theframework manager 440: (a) required, (b) impulse, and (c) vector. As thenames of the requests 675 mentioned above suggest, client requests 675generally correspond with client types that were created and describedabove.

In block 1405, the framework manager 440 may receive the data associatedwith a particular client request 675 such as one of the three mentionedabove: (a) required, (b) impulse, and (c) vector. The data associatedwith a required request generally comprises a scalar value that ispassed from the required client 648 to a particular resource 601. Forexample, a required request may comprise a certain number of millions ofinstructions per second (MIPs). An impulse request comprises a requestto complete some activity within a certain period of time without anydesignation of a start time or stop time. Data for a vector requestgenerally comprises an array of multiple actions that are required to becompleted in series or in parallel. A vector request may comprise anarbitrary length of values. A vector request usually has a size valueand an array of values. Each resource of a node 601 may be extended tohave a pointer field in order to support a vector request. In the “C”programming language, the pointer field is supported by the unionfunction as understood by one of ordinary skill in the art.

Next, in block 1410, the framework manager 440 issues the requestthrough the client 648 that was created by the method described above inconnection with FIG. 11. Subsequently, in block 1415, the frameworkmanager 440 double buffers the request data being passed through theclient if the request is a required type or a vector type. If therequest is an impulse type, then block 1415 is skipped by the frameworkmanager 440.

For required requests, in this block 1415, values from a prior requestare maintained in memory so that the framework manager 440 may determineif there is any difference between the previous requested values in thecurrent set of requested values. For vector requests, prior requests areusually not maintained in memory, although a resource of a node 601 maymaintain it as desired for a particular implementation. Therefore, block1415 is optional for vector types of requests.

In block 1420, the framework manager 440 calculates the delta ordifference between the previous set of requested values in the currentset of requested values. In decision block 1425, the framework managerdetermines if the current set of requested values is identical to theprevious set of requested values. In other words, the framework manager440 determines if a difference exists between the current set ofrequested values and the previous set of requested values. If there isno difference between the current set and previous set of requestedvalues, then the “Yes” branch is followed (which skips blocks 1430through block 1470) to block 1475 in which the process ends.

If the inquiry to decision block 1425 is negative, meaning that the setof requested values are different relative to the set of pre-previousrequested values, then the “No” branch is followed to decision block1430.

In decision block 1430, the framework manager 440 determines if thecurrent request is an asynchronous request. If the inquiry to decisionblock 1430 is negative, then the “No” branch is followed to block 1440in which the resource 601 corresponding to the client request 675 islocked by the framework manager 440. If the inquiry to decision block1430 is positive, meaning that the current request is asynchronousrequest type, then the “Yes” branch is followed to block 1435 in whichthe request may be pushed onto another thread and may be executed byanother core if a multi-core system, like that of FIG. 1, is currentlymanaged by the framework manager 440. Block 1435 has been illustratedwith dashed lines to indicate that this step may be optional if the PCD100 is a single core central processing system.

Subsequently, in block 1440, the resources 601 corresponding to therequest 675 is locked by the framework manager 440. Next, in block 1445,the resource 601 executes the update function which generallycorresponds to the plug-in data of the resource array data received inblock 1130 of FIG. 9. The update function generally comprises a functionresponsible for the new resource state in light of a new client request.The update function compares its previous state with the requested statein the client request. If the requested state is greater than theprevious state, then the update function will perform the clientrequest. However, if the requested state is equal to or less than thecurrent state and which the resource is operating at, then the clientrequest will not be performed in order to increase the efficiency sincethe old state achieves or satisfies the requested state. An updatefunction takes a new request from the client and aggregates it with allthe other active requests to determine the new state for the resource.

As an example, multiple clients may be requesting a bus clock frequency.The update function for the bus clock would usually take the maximum ofall the client requests and use that as the new desired state for thebus clock. It is not the case that all resources will use the sameupdate function, although there are some update functions that will beused by multiple resources. Some common update functions are to take themaximum of client requests, to take the minimum of client requests andto sum the client request. Or resources may define their own customupdate function if their resource needs to aggregate requests in someunique way.

Next, in block 1450, the framework manager 440 passes the data to theresource corresponding to the client 648 so that the resource mayexecute the driver function which is specific to the resource of a node601. A driver function applies the resource state as computed by theupdate function. This may entail updating hardware settings, issuingrequests to dependent resources, calling legacy functions or somecombination of the above.

In the previous example, the update function computed the requested busclock frequency. The driver function may receive that requestedfrequency and it may update the clock frequency control HW to run atthat frequency. Note that sometimes it is not possible for the driverfunction to meet the exact requested state that update function hascomputed. In this case, the driver function may choose the frequencythat best meets the request. For example, the bus clock HW may only beable to run at 128 MHz and 160 MHz, but the requested state might be 150MHz. In this case, the driver function should run at 160 MHz, as thatexceeds the requested state.

Next, in block 1455, the framework 440 receives state control from theresource which has executed the driver function in block 1450.Subsequently, in block 1460, if defined against the resource, events 690may be triggered so that data is passed back to the client 648 whichcorresponds to the event 690. Events may be processed in another thread.This may minimize the amount of time spent with the resources locked andallows for parallel operation in a multi-core system as illustrated inFIG. 1. One or more events 690 may be defined against a resource in amanner similar to how a request may be defined against a resource asdescribed in this method 1400. In other words, the event creationprocess may largely parallel the client creation process. One thing thatis different with the events is that it is possible to define eventsthat only get triggered when certain thresholds are crossed.

This defining of events that only get triggered based on thresholdsallows for notification of when a resource is getting oversubscribed (ithas more concurrent users than it can support) which is indicative of asystem overloading condition, or when a resource goes low/off, which mayallow other things to be shut off, restore functionality that wasdisabled when the system became oversubcscribed, etc. Because the eventregistration may be done with thresholds, it reduces the amount of workthe system has to do on event notification to only happen when there issomething really necessary. It is also possible to register for an eventon every state change.

Next, in optional block 1465, if the request being processed is a vectorrequest, then this optional block 1465 is usually performed. Optionalblock 1465 generally comprises a check or determination to assesswhether the vector pointer is still positioned on the same data that theuser passed into the vector. If the inquiry to this optional block 1465is positive, meaning that the pointer is still pointing to the same datawhich was passed by the user into the vector, then the pointer iscleared out so that references to old data is not maintained. Thisoptional block 1465 is generally performed to account for the doublebuffering block 1415 described above when a vector request is beingprocessed, compared to an impulse request and a required request.

Subsequently, in block 1470, the framework 440 unlocks the requestedresource so that other client requests 648 may be handled by the currentbut now released requested resource of a particular node 601. Theprocess then returns to the first block 1405 for receiving the nextclient request.

The above-described methods and data structures are essentially asapplicable to a multi-processor PCD 100 as they are to asingle-processor PCD 100. However, the remoting framework 300 (FIG. 3)may provide additional features that may enhance operation in amulti-processor embodiment. For example, the remoting framework 300 mayadvantageously render the details of inter-processor communicationtransparent to an application programmer or similar person. Thus, anapplication program, for example, may define a client that issues arequest on a target resource without having to include in the clientdefinition any identification of the processor domain that controls thatresource. Rather, the remoting framework 300 ensures that the requestwill reach the target resource regardless of which processor controlsthe client and which processor controls the target resource. Inaddition, the remoting framework 300 manages the inter-processorcommunication so that, for example, an application program need notinclude any instructions relating to the protocol or other aspects ofthe communication paths (e.g., buses) between processors. Furthermore,as different inter-processor communication paths may use differentprotocols, the remoting framework 300 allows the resource definition tospecify a protocol along with other aspects of the resource. These andother features relating to distributed resource management are describedbelow with regard to FIGS. 13-23.

FIG. 13 illustrates an example or instance in which a first resource1302, which is controlled by a first processor (not shown) serves as adistributed or remote resource corresponding to a second resource 1304,which is controlled by a second processor (not shown). The term“distributed resource” or “remote resource” is used in this disclosureto refer to a resource on one processor that corresponds to a “native”resource on another processor. The second resource 1304 in this exampleserves as a native resource to the second processor. A distributedresource is used as a means to access the corresponding native resource.In this example the term “resource” may be used interchangeably with theterm “node,” as it should be understood that a resource may be includedin a node.

A broken line 1301 illustrates a division between resources controlledby the first processor (to the left of the line 1301) and resourcescontrolled by the second processor (to the right of the line 1301). Thefirst resource 1302 is one of two or more resources that are controlledby the first processor. One such resource may be a protocol resource1306 on which the first resource 1302 depends. Likewise, the secondresource 1304 is one of two or more resources that are controlled by thesecond processor. In some embodiments, only a distributed resource andnot a native resource depends on a protocol resource. Therefore, in suchembodiments only the first (distributed) resource 1302 depends on aprotocol resource 1306. However, in other embodiments any resource maydepend on a protocol resource. Thus, in an alternative embodiment thesecond resource 1304 could also depend on a protocol resource (notshown). The first and second resources 1302 and 1306 may also depend onadditional resources in the same manner as described above with regardto resources or nodes in general, but such additional resources are notshown in FIG. 13 for purposes of clarity. Note that the resourcescontrolled by the first processor are defined by a first resource graph(i.e., a directed acyclic graph), and the resources controlled by thesecond processor are defined by a second such resource graph that doesnot share any resources with the first resource graph.

The first and second resources 1302 and 1304, under control of theirrespective processors, are capable of communicating information via acommunication path 1303. The communication path 1303 represents thecombination of the physical medium between the first and secondprocessors and the one or more layers of transport protocols used tocommunicate via that medium. Accordingly, any communications between thefirst resource 1302 and the second resource 1304 must conform to theprotocols. Protocol resources 1306 and 1308 define a protocol or maypoint to a protocol definition in a library (not shown). The remotingframework 300 and (main) framework 440 operate in conjunction with oneanother to manage the resources and communications between them. Asdescribed below, a client 1312, under control of the first processor,may issue one or more resource requests on the first resource 1302. Thefirst resource 1302 uses the functionality of the corresponding secondresource 1304 to service the resource request.

FIG. 14 is a flowchart illustrating a method 1400 for creating orinstantiating a distributed resource, such as the first resource 1302 ofFIG. 13. The flowchart of FIG. 14 is intended to illustrate featuresthat are in addition to or that augment the features described abovewith regard to methods for instantiating resources, such as the methodillustrated in FIGS. 7-10. Accordingly, except where it may be indicatedotherwise, any or all of the blocks in FIGS. 7-10 may be included butare not shown in FIG. 14 for purposes of clarity.

As indicated by block 1402, the framework managers 300 and 440 receivenode structure data that defines a node, such as that containing thefirst resource 1302. In the exemplary embodiment dependencies arehandled in essentially the same way as described above with regard toFIGS. 7-10, except that, as indicated by block 1406, protocol resourcesmay be instantiated at any time. A resource that depends on a protocolresource does not need to wait until its protocol resource isinstantiated. Instantiation of dependencies in the manner describedabove with regard to FIGS. 7-10 is illustrated generally by block 1408.

Although instantiation generally follows the methods described abovewith regard to FIGS. 7-10, it should be noted that a distributedresource cannot be instantiated until the native resource to which itcorresponds has been instantiated. Thus, instantiation of a nativeresource may delay instantiation of the distributed resource in the samemanner as instantiation of dependent resources may delay instantiationof a resource that depends on them. Also note that messages relating tothe state of instantiation of the native resource that are communicatedbetween the first and second processors via the communication path 1303and the framework managers 300 and 440 generally conform to thespecified protocol. For example, after the protocol resource 1306 on thefirst processor is instantiated, the first process, operating inaccordance with the remoting framework manager 300, may send a requestfor notification, encoded or otherwise conforming to the protocol, tothe second processor. When the second resource 1304 has beeninstantiated, the second processor, operating in accordance with theremoting framework manager 300, may respond to the request fornotification by sending a response to the first processor indicatingthat the second resource 1304 has been instantiated. The remotingframework manager 300 may manage such communications and others as partof the process of instantiating the software architecture.

The protocol resource 1306 on the first processor may include, amongother functions, a function to create a client, such as the client 1312shown in FIG. 13, and return a handle to the client that may be used bya thread of execution. A thread of execution (e.g., part of theexecution of an application program or other software element) mayinvoke the function to create such a client 1312. The thread may use theclient 1312 to issue resource requests and otherwise use the client 1312in the same manner as described above with regard to clients in general.The resource request is protocol-specific and allows the thread toaccess the second resource 1304 without the thread having to provide anyinformation relating to the protocol. From the perspective of the threadand its clients, the protocol may be irrelevant or transparent.

As indicated by block 1410, the frameworks 300 and 440 determine if anaggregation method is specified in the received node structure data. Ifit is determined that an aggregation method is specified, theaggregation method is set in the distributed and native resources(nodes), as indicated by block 1412. There are two aggregation types:local and proxy. In defining a resource, one of the two aggregationtypes may be selected. Accordingly, in instantiating a resource (node),the resource is set to perform either local aggregation or remoteaggregation.

A resource performs local aggregation by applying an algorithm tomultiple resource requests that it may receive “concurrently.” In thiscontext, two (or more) requests are “concurrent” for the time duringwhich they both remain active. For example, a first processor may issuea resource request to set its speed to 50 MIPS, and before the firstprocessor's request has been completed or otherwise terminated a secondprocessor may issue a resource request to set its speed to 100 MIPS.Aggregation may be performed in accordance with a method such as addingthe argument of each of the multiple concurrent resource requests, bydetermining the maximum argument from among those of all the multipleresource requests, by determining the minimum argument from among thoseof all the multiple resource requests, or by any other suitable method.The aggregation method may be specified or defined along with theaggregation type in the node structure data that defines the resource(node).

The node structure data may indicate that the node is to be instantiatedas a proxied node or a non-proxied node. The manner in which thisfeature may be used is described below with regard to FIGS. 16-17. Asindicated by block 1414, the node type is set to the indicated type. Inthe case of a non-proxied node, client requests are aggregated locallyin a manner determined by the node structure, and a driver function isused that sends the locally aggregated request to the native resource.Queries and events are handled by the distributed resource. In the caseof a proxied node, client requests are not aggregated but instead aresent individually to the native resources. Additionally, all queries andevents are forwarded to the native resource.

As indicated by block 1416, any remaining steps in the instantiationprocess occur. Such aspects of instantiating the distributed node may beessentially the same as described above with regard to FIGS. 7-10. Asindicated by block 1418, if additional nodes are defined, the methodrepeats or continues for those nodes.

FIG. 15 is a flowchart illustrating a method 1500 for servicing a clientrequest. The flowchart of FIG. 15 is intended to illustrate featuresthat are in addition to or that augment the features described abovewith regard to methods for servicing client requests, such as the methodillustrated in FIG. 12. Accordingly, except where it may be indicatedotherwise, any or all of the blocks in FIG. 12 may be included but arenot shown in FIG. 15 for purposes of clarity.

As indicated by block 1502, the distributed resource, such as that ofthe first node 1302 in FIG. 13, receives a client request. As indicatedby block 1504, it is determined whether the aggregation type associatedwith the requested resource is local or remote. If the aggregation typeis local, then the requested resource aggregates the request argumentwith others occurring within the same window, as indicated by block1506. As described above, aggregation relates to handling concurrentresource requests. If the aggregation type associated with the requestedresource is remote, then it will be left up to the corresponding nativeresource, such as the second resource 1304 in FIG. 13, to aggregate therequest with others.

Whether local or remote, aggregation implicates three sequential statesof a client request: (1) Request Issued, (2) Request in Progress and (3)Request Applied. In an instance in which client requests are issuedconcurrently, i.e., two client requests each begin the Request Issuedstate at effectively the same time or within the above-referenced windowof each other, the client request that occurred first causes therequested resource to be locked, and the client request that occurredsecond is handled after the client request that occurred first. A clientrequest is handled or serviced during the Request In Progress state.After the client request has been completed, the client request isassigned the Request Applied state. Aggregation comes into play in aninstance in which multiple concurrent client requests have reached theRequest Applied state. For example, if a resource has been defined asusing the above-referenced maximum aggregation method, and client “A”requests 50 MIPS while, perhaps a few microseconds later, client “B”requests 100 MIPS, these initial requests will be serialized.Accordingly, when the first client request is processed, the resourcewill be set to the argument of the first client request or 50 MIPS.Then, when the second client request is processed, the resource, inaccordance with the maximum aggregation method, will be set to 100because 100 is the maximum of 50 and 100. Thereafter, when both of theseinitial client requests are in the Request Applied state, client “B” mayissue another client request for 25 MIPS. The requested resource, inaccordance with the maximum aggregation method, will be set to 50because 50 is the maximum of 50 and 25.

As indicated by block 1508, it is determined whether the requestedresource depends on a protocol resource, such as the protocol resource1306 in FIG. 13. If the requested resource depends on a protocolresource, then the protocol resource is invoked and used to conform theresource request to the protocol that the protocol resource defines, asindicated by block 1510 and 1512, respectively. As indicated by block1514, in conformance with the protocol, a resource request reflectingthe aggregation result (result of block 1506) is sent or, if the remoteresource is to perform the aggregation, the resource request isforwarded, to the native resource, such as the second resource 1304 inFIG. 13. The driver function (not shown) of the distributed resourceinvokes the protocol.

Although not shown in FIG. 15, events involving distributed resourcesmay be handled in essentially the same manner as described above withregard to FIG. 12. Events of a type that monitor for a value crossing athreshold may be especially useful in combination with a proxiedresource, as described below.

FIG. 16 is a flowchart illustrating a method 1600 for servicing a statequery on a distributed resource of the non-proxied type. State queriesare managed by the framework 440 as described above with regard to FIGS.5-6. The flowcharts of FIGS. 16-17 are intended to illustrate featuresthat are in addition to or that augment the features described abovewith regard to FIGS. 5-6. Accordingly, except where it may be indicatedotherwise, any or all of the features described above with regard toFIGS. 5-6 may be included but are not shown in FIGS. 16-17 for purposesof clarity.

As indicated by block 1602, the distributed resource, such as that ofthe first node 1302 in FIG. 13, receives a state query. In this example,the first node 1302 represents a non-proxied node or resource. Asindicated by block 1604, the state query is forwarded to thecorresponding native resource such as the second resource 1304 in FIG.13. As indicated by block 1606, the state of the native resource is sentback to the distributed resource in response to the state query. Asindicated by block 1608, the distributed resource may then provide astate indication, which represents the state of the native resource, tothe query requestor (client).

FIG. 17A is a flowchart illustrating a first portion of a method 1700for servicing a state query on a distributed resource of the proxiedtype. As indicated by block 1702, the distributed resource, such as thatof the first node 1302 in FIG. 13, receives a state query. In thisexample, the first node 1302 represents a proxied node or resource. Asindicated by blocks 1704 and 1706, respectively, each time thedistributed resource receives an indication of the native resource'sstate, the distributed resource updates its state to reflect the nativeresource's state. As indicated by block 1608, the distributed resourceprovides an indication of its own state to the query requestor (client).Thus, in the case of a proxied distributed resource, its state onlychanges when it receives an notification of a change in state from thecorresponding native resource.

As indicated by block the state query is forwarded to the correspondingnative resource such as the second resource 1304 in FIG. 13. Asindicated by block 1606, the state of the native resource is sent backto the distributed resource in response to the state query.

FIG. 17B is a flowchart illustrating a second portion of the method 1700for servicing a state query on a distributed resource of the proxiedtype. This second portion reflects the perspective of the nativeresource and operates asynchronously and in parallel with the firstportion illustrated in FIG. 17A. As indicated by block 1710, the stateof a native resource, such as the second node 1304 of FIG. 13, ismonitored. As indicated by blocks 1712 and 1714, respectively, if achange in state of the native resource is detected, an indication of thestate of the native resource is sent to the corresponding distributedresource.

The use of proxied distributed resources in appropriate instances maypromote the desirable goal of minimizing inter-processor traffic,because state information is only sent from the native resource'sprocessor to the distributed resource's processor when the nativeresource's state changes. In contrast, in the case of a non-proxiedresource, a state query is sent and state information is returned eachtime the distributed resource receives a state query. Proxied resourcesmay be used in instances in which, for example, it is the state of thedistributed resource, rather than the corresponding native resource,that is most relevant to the task to be performed under control of thefirst processor.

As noted above with regard to FIGS. 5-6, events and queries are relatedaspects of the software architecture. Events of a type that monitor fora value crossing a threshold may be especially useful in combinationwith a proxied resource, because inter-processor messages are only sentwhen the when the native resource's state crosses a threshold ratherthan every time the native resource's state changes.

In some instances it may be desirable to group or “batch” a number ofseparate resource requests together in a single “transaction of resourcerequests.” In instances in which the multiple resource requests areagainst remote or distributed resources controlled by the same processoras each other, transactionizing the resource requests may help minimizethe number of messages transmitted through the communication path 1303(FIG. 13) between the first and second processors. As well understood bya person of ordinary skill in the art, a “transaction” is an action thatoccurs in accordance with properties commonly referred to by the acronymACID: atomicity, consistency, isolation and durability. Atomicity meansthat either all of the constituent steps of the transaction areperformed or none of them are performed, so as to avoid problemsassociated with partially performed transactions. Consistency means thata transaction will take the system from one consistent/coherent state toanother. Isolation means that other operations cannot access data thathas been modified during a transaction that has not yet completed.Locking access to data is commonly used to ensure the isolation propertyof a transaction. As described above, a resource is locked when it isaccessed in response to a resource request and unlocked when theresource request is completed. Durability relates to recovery fromsystem failures. The term “transaction” is used in this specification torefer to a group of resource requests that are performed together inaccordance with at least the properties of atomicity and isolation. Theframework or programming interface for resource request transactionssupports consistency in its design, but whether the system reaches aconsistent state following a transaction is dependent on the actions ofthe individual transactionized resource requests and thus is notnecessarily a property of the framework or programming interface.

Providing a transaction of resource requests may involve two aspects. Inone aspect, a transaction of resource requests may be defined. Indefining a transaction of resource requests, the transaction of resourcerequests is assigned a unique name or identifier, a locking type isspecified, and the resources that may be involved in the transaction ofresource requests are listed. The result of defining a transaction ofresource requests may be a handle that can be referenced by an entity inorder to issue (or create an instance of) the transaction of resourcerequests.

The second aspect of providing a transaction of resource requestsrelates to issuing or creating an instance of the defined transaction ofresource requests. A transaction of resource requests may be issued by aresource (e.g., as a batch of resource requests to other resources itdepends upon) or, alternatively, by an entity other than a resource,such as by an executing thread or by a device driver that is notincluded in one of a resources defined by the above-described resourcegraph of the PCD 100. A transaction of resources request is, like otherresource requests, a type of client request. Any entity that is capableof issuing a client request (or, in common computer science parlance,that “owns” the client) in the manner described above may issue atransaction of resource requests.

To issue a transaction of resource requests, the resource, thread orother such entity executes software code that “starts” or sets up thepreviously defined transaction of resource requests, issues resourcerequests to the various resources that are defined to be part of thetransaction of resource requests, and then ends the transaction ofresource requests, initiating processing of the batched requests andending the transaction of resource requests. The process of ending atransaction of resource requests may involve transmitting the batch ofrequests from the first processing entity to the second processingentity, processing the batched requests at the second processing entity,waiting at the first processing entity for a notification of completionof processing, and then on receipt of the notification, executing anyupdates to local resource proxies or registered callbacks at the firstprocessing entity.

FIG. 18 is a flowchart illustrating a method 1800 for issuing atransaction of resource requests. The method 1800 is described belowwith reference to exemplary pseudocode. The following is an example ofpseudocode that generally represents code that is executed by an entityissuing a transaction of resource requests:

BEGIN_TRANSACTION(HANDLE)   REQUEST(A)   REQUEST(B)   REQUEST(C)END_TRANSACTION(HANDLE)

As indicated by block 1802 in FIG. 18, an indication of a sequence ofevents is provided. For example, the sequence of events may be providedby means of the execution of the code represented by the pseudocodeabove. The sequence of events that is indicated includes: an indicationof the beginning of the transaction of resource requests (represented inthe exemplary pseudocode by “BEGIN_TRANSACTION(HANDLE)”; an indicationof the end of the transaction of resource requests (represented in theexemplary pseudocode by “END_TRANSACTION”; and indications of the two ormore resource requests that are to occur as part of the transaction,i.e., between the beginning of the transaction and the end of thetransaction. The pseudocode “BEGIN_TRANSACTION(HANDLE)” represents thesetting up of a transaction of resource requests on a handle that hasbeen defined in the manner described above. As the process of issuing atransaction of resource requests spans these many steps, any transactionof resource requests on a handle is to be performed in accordance withthe locking type associated with that handle and the resourcesassociated with that handle at the time the transaction of resourcerequests was defined.

Although not reflected in the pseudocode above for purposes of clarity,it is useful to note that a transaction of resource requests may includeconditional logic. For example, the code representing a transaction ofresource requests may include logic having the form “IF (condition) THEN(issue resource request)” or similar logic that, when evaluated inresponse to input conditions, results in providing requests to a subsetof the resources that are listed in the definition of the transaction ofresource requests. In other words, a transaction of resource requestsmay be defined that includes a certain resource request only ifspecified conditions are met at the time of issuance of the transactionof resource requests, i.e., at the time that code is executed thatrepresents the transaction of resource requests. For example, atransaction of resource requests may be defined as involving resourcesA, B, C and D, but evaluation of conditional logic in a given instancemay provide only indications of resource requests against resources A, Band C. That is, as a result of the evaluation of the conditional logicin this exemplary instance of a transaction of resource requests, aresource request against resource D may not be included in the actualtransaction of resource requests. Not all resources that are defined aspotentially involved in a transaction of resource requests may be neededin all instances. For purposes of clarity, the exemplary pseudocodeabove shows only the resource requests that are indicated in a giveninstance and does not show any conditional logic. Nevertheless, itshould be understood that a transaction of resource requests may includeany number of resource requests and any suitable conditional logic thatmay determine which resource requests are included in a given instance.

As indicated by block 1803, a queue for resource requests involved inthe transaction of resource requests is set up. As indicated by block1804, each resource involved in a transaction of resource requests islocked for the duration of the transaction of resource requests. Asdescribed below, resources may be locked in accordance with differentlocking types, such as a first locking type referred to below as“pessimistic locking” or a second locking type referred to below as“lazy locking.” As described above, the locking type is defined when thetransaction of resource requests is defined. Thus, when the transactionof resource requests is issued, it will have been predetermined at thetime of issuance whether the transaction of resource requests is to beperformed in accordance with the pessimistic locking method or,alternatively, in accordance with the lazy locking method. Depending onthe locking method, the resources involved in the transaction ofresource requests may be locked at different times, as described infurther detail below. Also, depending on the locking type, either all ofthe resources defined as being part of the transaction of resourcerequests are locked (pessimistic locking) or only the subset of theseresources to which requests are issued as part of the transaction arelocked (lazy locking).

In another embodiment, when the locking type associated with thetransaction of resource requests is “lazy” (as described further below),the entity defining and issuing the transaction of resource requestsneed not be constrained in having to define or list all the resourcesthat may be part of the transaction, during the definition aspect of atransaction of resource requests. It is wholly possible for theresources that are (or in the case, become) part of the transaction tobe dynamically included in the transaction, by virtue of one or morerequests to these resources being issued in context of the transaction.As an example, in the pseudocode above, the entity issuing thetransaction need not define A, B and C as being part of the transaction,during the definition aspect, if the locking type it associates with thetransaction is “lazy.” It can begin the transaction and then issuerequests to two or more of A, B and C. These resources then implicitlybecome part of the transaction of resource requests, and the requests tothem are only batched and not processed immediately. Thus, in thisembodiment, it is possible to construct a “dynamic” or “run-timedefined” transaction, in the sense that any number of resources can beadded to the transaction, after beginning the transaction, withouthaving to define them all upfront. As will be evident from thedescription of locking types further below, such a “dynamic” or“run-time defined” transaction of resource requests cannot be of the“pessimistic” locking type.

As indicated by block 1806, information associated with each of theresource requests included in the transaction of resource requests isadded to the queue. With reference to the pseudocode above, in aninstance in which “REQUEST(A)” represents a request against resource Afor, for example, processing throughput of 50 MIPS, resource A (or itsdistributed counterpart in an instance in which resource A is controlledby a processor other than that which is issuing the transaction ofresource requests) may add a value of 50 to the queue. Likewise, anysuitable parameters associated with other resource requests that arepart of the transaction of resource requests are added to the queue atthe time of execution of the corresponding code, such as the coderepresented by the pseudocode “REQUEST(B).” For purposes of clarity, thepseudocode above does not reflect all parameters that may be included ina resource request, such as a parameter representing the “50” in thisexample.

It should be noted that the locking and adding-to-queue steps indicatedby blocks 1804 and 1806, respectively, may be performed in any order andinvolve one or more sub-steps. For example, as described below, in atransaction of resource requests that has been defined to be of thepessimistic locking type, all resources indicated in the definition ofthe transaction of resource requests are locked before any informationassociated with the resource requests is added to the queue. However, ina transaction of resource requests that has been defined to be of thelazy locking type, each resource request in turn results in locking ofthe requested resource and adding information associated with only thatresource request to the queue. In other words, in a transaction ofresource requests, the locking and adding-to-queue steps may beperformed in an alternating manner with each other. Pessimistic and lazylocking are described in further detail below.

As indicated by block 1808, the queue is transmitted to a recipient inresponse to the indication of the end of the transaction. The recipientmay be, for example, another processor. The recipient may be, forexample, another processor, i.e., a processor other than the processorfrom which the transaction of resource requests is issued. In such aninstance, the queue takes the place of multiple messages associated withmultiple resource requests that would have been issued if the resourcerequests had not been transactionized in the manner described above. Atthe issuing entity, the thread of execution is blocked until there isnotification from the recipient that the queue of requests has beenprocessed. Then, any residual processing at the issuing entity iscompleted (this may involve any updates to local resource proxies orexecuting any registered callbacks), and the transaction is deemedcompleted. All of this is represented by the “END_TRANSACTION(HANDLE)”in the pseudocode above.

As indicated by block 1810, all of the resources indicated in thetransaction of resource requests are unlocked following the end of thetransaction, as represented by the “END_TRANSACTION” in the pseudocodeabove. Thus, the resources are unlocked after the queue is transmittedand batched requests processed.

It should be noted that while this text refers to resource requestsissued within a transaction of resource requests, as being added to aqueue, the “queue” need not possess any of the properties of a standardqueue, such as ordering of elements in a first-in-first-out manner. Thisis not to say that, in a particular implementation, a standard queuecannot be used to batch requests. While such a queue may well be used,in other implementations, requests may be added into any sort ofcontainer or buffer that can receive elements one or more at a time andstore them until eventual transmission or processing. In such cases, the“queue” may be considered a bag or bucket of resource requests.

FIG. 19 illustrates an exemplary resource graph 1900 for an exemplarytransaction of resource requests that includes resource requests forresources A, B and C. For example, resources A, B and C in FIG. 19 maybe those corresponding to “REQUEST(A),” “REQUEST(B)” and “REQUEST(C)” inthe exemplary pseudocode above.

In an instance in which the transaction of resource requests has beendefined to be of the lazy locking type, in response to a first resourcerequest 1902 against resource A, resource A becomes locked, and theinformation associated with the first resource request 1902 is added tothe above-referenced queue. Resource A then issues a second resourcerequest 1904 against resource B because resource A depends on resourceB. In response to the second resource request 1904, resource B becomeslocked, and the information associated with the second resource request1904 is added to the queue. Resource A then issues a third resourcerequest 1906 against resource C because resource C depends on resourceB. In response to the third resource request 1906, resource C becomeslocked, and the information associated with the third resource request1906 is added to the queue. With reference to the pseudocode above:resource A is locked at the time the code represented by the pseudocode“REQUEST(A)” is executed; resource B is locked at the time the coderepresented by the pseudocode “REQUEST(B)” is executed; and resource Cis locked at the time the code represented by the pseudocode“REQUEST(C)” is executed.

The lazy locking method may be satisfactory if the properties of theresource graph that defines the set of the resources involved in thetransaction of resource requests preclude the possibility of a deadlockcondition. FIG. 20 illustrates an exemplary resource graph 2000 that issimilar to resource graph 1900 but that does not preclude thepossibility of a deadlock condition. With further reference to the eventtimeline 2100 of FIG. 21, in an exemplary instance, a first thread and asecond thread each request resources indicated by the resource graph2000 (FIG. 20). A first thread issues a first (transactionized) resourcerequest 2002 (FIG. 20) against resource A, which locks resource A. Asresource A depends on resource B, resource A then issues a secondresource request 2004 against resource B, thereby locking resource B. Asresource B depends on resource D, resource B then issues a thirdresource request 2006 against resource D, thereby locking resource D.Then, a second thread issues a fourth resource request 2008 againstresource C, thereby locking resource C. As resource C depends onresource D, resource C then issues a fifth resource request 2010 againstresource D. However, as resource D has already been locked as a resultof resource request 2006, resource request 2010 is “blocked” andtherefore cannot be completed until resource D becomes unlocked. But asixth resource request 2012 against resource C as a result of thedependence of resource A on resource C, issued in the context of thefirst thread, will also be blocked because resource C was locked as aresult of resource request 2008 by the second thread. In this instance,there is a deadlock condition because the first thread cannot completeits resource request 2002 until the resources on which resource Adepends are unlocked, yet the second thread cannot complete its resourcerequest 2008 until the resources on which resource C depends areunlocked.

To avoid the possibility of a deadlock condition in such an instance, atransaction of resource requests may be defined to be of the pessimisticlocking type rather than the lazy locking type. In a transaction ofresource requests of the pessimistic locking type, all resourcesindicated in the transaction of resource requests are locked in responseto the indication of the beginning of the transaction, before anyindications of the individual resource requests (or before anyindividual resource requests are issued). Thus, with reference to thepseudocode above and to FIGS. 20 and 22, resources A, B and C are alllocked in response to execution of the code represented by“BEGIN_TRANSACTION.” The resources may be locked in an order indicatedby a topological sort of the resource graph. As methods of topologicallysorting a directed acyclic graph are well understood by a person ofordinary skill in the art, they are not described in this specificationin further detail. Any suitable topological sort method may be used. Inan exemplary instance, represented by the event timeline 2200 of FIG.22, the results of the topological sort of the resource graph 2000 (FIG.20) may be, for example: A, B, C, D. Thus, in response to an indicationof the beginning of the transaction of resource requests againstresource A: resource B is locked after resource A is locked; thenresource C is locked after resource B is locked; and finally resource Dis locked after resource C is locked. After all of the resources A, B, Cand D are locked, the indicated resource requests may proceed againstresources B, C and D. In another embodiment (or implementation), theresources may be locked in the order indicated by the topological sort,as part of the setup of the transaction of resource requests,represented in the pseudocode by “BEGIN_TRANSACTION.”

FIG. 23 is a flowchart illustrating a method 2300 for a resource torespond to a resource request. The resource referred to with regard tothe method 2300 may be any of, for example, the resources A, B and Creferenced in the pseudocode above. As indicated by block 2302, theresource receives the resource request. For example, resource A mayreceive a request in response to execution of code represented by“REQUEST(A)” in the pseudocode above. If the resource is involved in atransaction of resource requests of the lazy locking type, the resourceis locked at this time. However, locking is not shown in FIG. 23 becausethe method 2300 represents the perspective of the resource against whichthe resource request is issued, and the resource may be locked andunlocked by a control entity that is not part of the resource. Forexample, an entity included in the framework manager 440 may controllocking and unlocking of resources and the handling of any deadlocksthat may occur, as part of the control functions involved in routingmessages to and from resources.

As indicated by block 2304, the resource determines whether it isinvolved in a transaction of resource requests. A status indicator maybe included in each resource that may be set at the beginning of atransaction of resource requests to indicate that the resource isincluded in the transaction of resource requests. In another embodiment(or implementation), a status indicator may be set in the thread afterit executes the pseudocode represented by “BEGIN_TRANSACTION,”indicating that the current thread has begun a transaction of resourcerequests. If the resource determines that it is not involved in atransaction of resource requests, then the resource performs theresource request in the normal manner, as indicated by block 2306. Thatis, the resource may perform and complete the resource request in thenormal manner described above with regard to FIGS. 12 and 15. Note that,as described above with regard to FIG. 12, at the beginning ofperformance of a (non-transactionized) resource request the resource islocked, and at the completion of the resource request, the resource isunlocked.

If the resource determines that it is involved in a transaction ofresource requests, then the resource determines whether theabove-referenced queue has been created (by, for example, anotherresource or by the pseudocode represented by “BEGIN_TRANSACTION”), asindicated by block 2308. If the resource determines that a queue doesnot exist, then the resource creates a queue, as indicated by block2310. As indicated by block 2312, a resource involved in a transactionof resource requests then adds the information associated with therequest against it to the queue. Note that the resource is in a lockedstate prior to adding the information to the queue as a result of eitherthe lazy locking method or the alternative pessimistic locking method.The lock is not removed after the resource adds the information to thequeue. Rather, as described above, the lock is removed only upon anindication of the end of the transaction and transmittal of the queueto, and subsequent processing of the batch of requests at, anotherprocessor or other recipient.

In view of the disclosure above, one of ordinary skill in the art isable to write computer code or identify appropriate hardware and/orother logic or circuitry to implement the distributed resourcemanagement system and method without difficulty based on the flowchartsand associated description in this specification, for example.Therefore, disclosure of a particular set of program code instructionsor detailed hardware devices is not considered necessary for an adequateunderstanding of how to make and use the distributed resource managementsystem and method. The inventive functionality of the claimed computerimplemented processes is explained in more detail in the abovedescription and in conjunction with the drawing figures, which mayillustrate various process flows. Further, the processors 110, 126, 202,206, etc., in combination with the memory 112 and the instructionsstored therein may serve as a means for performing one or more of themethod steps described herein.

In one or more exemplary aspects, the functions described may beimplemented in hardware, software, firmware, or any combination thereof.If implemented in software, the functions may be stored on ortransmitted as one or more instructions or code on a computer-readablemedium. Computer-readable media include both computer storage media andcommunication media including any medium that facilitates transfer of acomputer program from one place to another. A storage medium may be anyavailable medium that may be accessed by a computer. By way of example,and not limitation, such computer-readable media may comprise RAM, ROM,EEPROM, CD-ROM or other optical disk storage, magnetic disk storage orother optical or magnetic storage devices, or any other medium that maybe used to carry or store desired program code in the form ofinstructions or data structures and that may be accessed by a computer.The term “disk” or “disc,” as used herein, includes but is not limitedto compact disc (“CD”), laser disc, optical disc, digital versatile disc(“DVD”), floppy disk and Blu-ray disc. Combinations of the above shouldalso be included within the scope of computer-readable media.

Although selected aspects have been illustrated and described in detail,it will be understood that various substitutions and alterations may bemade therein without departing from the spirit and scope of the presentdisclosure, as defined by the following claims.

1. A method for batching resource requests in a portable computingdevice having a plurality of resources, the method comprising:instantiating a plurality of nodes, each node having at least one of theplurality of resources, the plurality of resources defined by a directedacyclic graph, wherein each node of the directed acyclic graphrepresents an encapsulation of functionality of one or more of theplurality of resources, each edge of the directed acyclic graphrepresents a client request, and adjacent nodes of the directed acyclicgraph represent resource dependencies; and providing a transaction ofresource requests indicating two or more resources of the plurality ofresources defined by the directed acyclic graph.
 2. The method claim 1,wherein providing the transaction of resource requests comprises:providing an indication of a sequence of events including a beginning ofa transaction, an end of a transaction, and a plurality of resourcerequests between the beginning of the transaction and the end of thetransaction, each resource request indicating one or more of theplurality of resources defined by the directed acyclic graph; lockingthe resources indicated by the plurality of resource requests; addinginformation associated with each of the plurality of resource requeststo a queue; transmitting the queue to a recipient in response to theindication of the end of the transaction; and unlocking the plurality ofresources after transmitting the queue.
 3. The method of claim 2,wherein transmitting the queue to a recipient comprises transmitting thequeue from a first processing entity to a second processing entity. 4.The method of claim 2, wherein locking each resource indicated by theplurality of resource requests comprises locking all resources indicatedby the plurality of resource requests in response to an indication ofthe beginning of the transaction.
 5. The method of claim 4, wherein:transmitting the queue comprises transmitting the queue from a firstprocessing entity to a second processing entity; and locking eachresource indicated by the plurality of resource requests compriseslocking a plurality of local resources controlled by the firstprocessing entity corresponding to a plurality of remote resourcescontrolled by the second processing entity.
 6. The method of claim 4,wherein locking each resource indicated by the plurality of resourcerequests further comprises: sorting representations of the plurality ofresources indicated by the plurality of resource requests in accordancewith the directed acyclic graph; and locking all resources indicated bythe plurality of resource requests in an order corresponding to resultsof sorting the representations.
 7. The method of claim 2, whereinlocking each resource indicated by the plurality of resource requestscomprises locking a resource indicated by a resource request in responseto an indication of the resource request.
 8. The method of claim 7,wherein: transmitting the queue comprises transmitting the queue from afirst processing entity to a second processing entity; and locking eachresource indicated by the plurality of resource requests compriseslocking a plurality of local resources controlled by the firstprocessing entity corresponding to a plurality of remote resourcescontrolled by the second processing entity.
 9. A computer system forbatching resource requests in a portable computing device having aplurality of resources, the computer system comprising: a processingentity operable for: instantiating a plurality of nodes, each nodehaving at least one of the plurality of resources, the plurality ofresources defined by a directed acyclic graph, wherein each node of thedirected acyclic graph represents an encapsulation of functionality ofone or more of the plurality of resources, each edge of the directedacyclic graph represents a client request, and adjacent nodes of thedirected acyclic graph represent resource dependencies; and providing atransaction of resource requests indicating two or more resources of theplurality of resources defined by the directed acyclic graph.
 10. Thecomputer system claim 9, wherein providing the transaction of resourcerequests comprises: providing an indication of a sequence of eventsincluding a beginning of a transaction, an end of a transaction, and aplurality of resource requests between the beginning of the transactionand the end of the transaction, each resource request indicating one ormore of the plurality of resources defined by the directed acyclicgraph; locking the resources indicated by the plurality of resourcerequests; adding information associated with each of the plurality ofresource requests to a queue; transmitting the queue to a recipient inresponse to the indication of the end of the transaction; and unlockingthe plurality of resources after transmitting the queue.
 11. Thecomputer system of claim 10, wherein transmitting the queue to arecipient comprises transmitting the queue from a first processingentity to a second processing entity.
 12. The computer system of claim10, wherein locking each resource indicated by the plurality of resourcerequests comprises locking all resources indicated by the plurality ofresource requests in response to an indication of the beginning of thetransaction.
 13. The computer system of claim 12, wherein: transmittingthe queue comprises transmitting the queue from a first processingentity to a second processing entity; and locking each resourceindicated by the plurality of resource requests comprises locking aplurality of local resources controlled by the first processing entitycorresponding to a plurality of remote resources controlled by thesecond processing entity.
 14. The computer system of claim 12, whereinlocking each resource indicated by the plurality of resource requestsfurther comprises: sorting representations of the plurality of resourcesindicated by the plurality of resource requests in accordance with thedirected acyclic graph; and locking all resources indicated by theplurality of resource requests in an order corresponding to results ofsorting the representations.
 15. The computer system of claim 10,wherein locking each resource indicated by the plurality of resourcerequests comprises locking a resource indicated by a resource request inresponse to an indication of the resource request.
 16. The computersystem of claim 15, wherein: transmitting the queue comprisestransmitting the queue from a first processing entity to a secondprocessing entity; and locking each resource indicated by the pluralityof resource requests comprises locking a plurality of local resourcescontrolled by the first processing entity corresponding to a pluralityof remote resources controlled by the second processing entity.
 17. Acomputer system for batching resource requests in a portable computingdevice having a plurality of resources, the computer system comprising:means for instantiating a plurality of nodes, each node having at leastone of the plurality of resources, the plurality of resources defined bya directed acyclic graph, wherein each node of the directed acyclicgraph represents an encapsulation of functionality of one or more of theplurality of resources, each edge of the directed acyclic graphrepresents a client request, and adjacent nodes of the directed acyclicgraph represent resource dependencies; and means for providing atransaction of resource requests indicating two or more resources of theplurality of resources defined by the directed acyclic graph.
 18. Thecomputer system claim 17, wherein the means for providing thetransaction of resource requests comprises: means for providing anindication of a sequence of events including a beginning of atransaction, an end of a transaction, and a plurality of resourcerequests between the beginning of the transaction and the end of thetransaction, each resource request indicating one or more of theplurality of resources defined by the directed acyclic graph; means forlocking the resources indicated by the plurality of resource requests;means for adding information associated with each of the plurality ofresource requests to a queue; means for transmitting the queue to arecipient in response to the indication of the end of the transaction;and means for unlocking the plurality of resources after transmittingthe queue.
 19. The computer system of claim 18, wherein the means fortransmitting the queue to a recipient comprises means for transmittingthe queue from a first processing entity to a second processing entity.20. The computer system of claim 18, wherein the means for locking eachresource indicated by the plurality of resource requests comprises meansfor locking all resources indicated by the plurality of resourcerequests in response to an indication of the beginning of thetransaction.
 21. The computer system of claim 20, wherein: the means fortransmitting the queue comprises means for transmitting the queue from afirst processing entity to a second processing entity; and the means forlocking each resource indicated by the plurality of resource requestscomprises means for locking a plurality of local resources controlled bythe first processing entity corresponding to a plurality of remoteresources controlled by the second processing entity.
 22. The computersystem of claim 20, wherein the means for locking each resourceindicated by the plurality of resource requests further comprises: meansfor sorting representations of the plurality of resources indicated bythe plurality of resource requests in accordance with the directedacyclic graph; and means for locking all resources indicated by theplurality of resource requests in an order corresponding to results ofsorting the representations.
 23. The computer system of claim 18,wherein the means for locking each resource indicated by the pluralityof resource requests comprises means for locking a resource indicated bya resource request in response to an indication of the resource request.24. The computer system of claim 23, wherein: the means for transmittingthe queue comprises means for transmitting the queue from a firstprocessing entity to a second processing entity; and the means forlocking each resource indicated by the plurality of resource requestscomprises means for locking a plurality of local resources controlled bythe first processing entity corresponding to a plurality of remoteresources controlled by the second processing entity.
 25. A computerprogram product comprising a computer usable medium having a computerreadable program code embodied therein, said computer readable programcode adapted to be executed to implement a method for batching resourcerequests in a portable computing device having a plurality of resources,said method comprising: instantiating a plurality of nodes, each nodehaving at least one of the plurality of resources, the plurality ofresources defined by a directed acyclic graph, wherein each node of thedirected acyclic graph represents an encapsulation of functionality ofone or more of the plurality of resources, each edge of the directedacyclic graph represents a client request, and adjacent nodes of thedirected acyclic graph represent resource dependencies; and providing atransaction of resource requests indicating two or more resources of theplurality of resources defined by the directed acyclic graph.
 26. Thecomputer program product of claim 25, wherein providing the transactionof resource requests comprises: providing an indication of a sequence ofevents including a beginning of a transaction, an end of a transaction,and a plurality of resource requests between the beginning of thetransaction and the end of the transaction, each resource requestindicating one or more of the plurality of resources defined by thedirected acyclic graph; locking the resources indicated by the pluralityof resource requests; adding information associated with each of theplurality of resource requests to a queue; transmitting the queue to arecipient in response to the indication of the end of the transaction;and unlocking the plurality of resources after transmitting the queue.27. The computer program product of claim 26, wherein transmitting thequeue to a recipient comprises transmitting the queue from a firstprocessing entity to a second processing entity.
 28. The computerprogram product of claim 26, wherein locking each resource indicated bythe plurality of resource requests comprises locking all resourcesindicated by the plurality of resource requests in response to anindication of the beginning of the transaction.
 29. The computer programproduct of claim 28, wherein: transmitting the queue comprisestransmitting the queue from a first processing entity to a secondprocessing entity; and locking each resource indicated by the pluralityof resource requests comprises locking a plurality of local resourcescontrolled by the first processing entity corresponding to a pluralityof remote resources controlled by the second processing entity.
 30. Thecomputer program product of claim 28, wherein locking each resourceindicated by the plurality of resource requests further comprises:sorting representations of the plurality of resources indicated by theplurality of resource requests in accordance with the directed acyclicgraph; and locking all resources indicated by the plurality of resourcerequests in an order corresponding to results of sorting therepresentations.
 31. The computer program product of claim 26, whereinlocking each resource indicated by the plurality of resource requestscomprises locking a resource indicated by a resource request in responseto an indication of the resource request.
 32. The computer programproduct of claim 31, wherein: transmitting the queue comprisestransmitting the queue from a first processing entity to a secondprocessing entity; and locking each resource indicated by the pluralityof resource requests comprises locking a plurality of local resourcescontrolled by the first processing entity corresponding to a pluralityof remote resources controlled by the second processing entity.
 33. Amethod for batching resource requests in a portable computing devicehaving a plurality of resources, the method comprising: instantiating aplurality of nodes, each node having at least one of the plurality ofresources, the plurality of resources defined by a directed acyclicgraph, wherein each node of the directed acyclic graph represents anencapsulation of functionality of one or more of the plurality ofresources, each edge of the directed acyclic graph represents a clientrequest, and adjacent nodes of the directed acyclic graph representresource dependencies; receiving a resource request indicating aresource defined by the directed acyclic graph; determining if theresource request is associated with a transaction; if the resourcerequest is not associated with a transaction, performing the resourcerequest on the indicated resource; and if the resource request isassociated with a transaction, adding information associated with theresource requests to a queue instead of performing the resource requeston the indicated resource.
 34. The method of claim 33, whereinperforming the resource request on the indicated resource comprises:locking the indicated resource; initiating the resource request on theindicated resource; and unlocking the indicated resource in response toan indication of completion of the resource request.
 35. The method ofclaim 33, further comprising: determining if a queue exists prior toadding information associated with the resource requests to the queue;and creating the queue if the queue does not exist and the resourcerequest is associated with a transaction.
 36. A computer system forbatching resource requests in a portable computing device having aplurality of resources, the computer system comprising: a processingentity operable for: instantiating a plurality of nodes, each nodehaving at least one of the plurality of resources, the plurality ofresources defined by a directed acyclic graph, wherein each node of thedirected acyclic graph represents an encapsulation of functionality ofone or more of the plurality of resources, each edge of the directedacyclic graph represents a client request, and adjacent nodes of thedirected acyclic graph represent resource dependencies; receiving aresource request indicating a resource defined by the directed acyclicgraph; determining if the resource request is associated with atransaction; if the resource request is not associated with atransaction, performing the resource request on the indicated resource;and if the resource request is associated with a transaction, addinginformation associated with the resource requests to a queue instead ofperforming the resource request on the indicated resource.
 37. Thecomputer system of claim 36, wherein performing the resource request onthe indicated resource comprises: locking the indicated resource;initiating the resource request on the indicated resource; and unlockingthe indicated resource in response to an indication of completion of theresource request.
 38. The computer system of claim 36, wherein theprocessing entity is further operable for: determining if a queue existsprior to adding information associated with the resource requests to thequeue; and creating the queue if the queue does not exist and theresource request is associated with a transaction.
 39. A computer systemfor batching resource requests in a portable computing device having aplurality of resources, the computer system comprising: means forinstantiating a plurality of nodes, each node having at least one of theplurality of resources, the plurality of resources defined by a directedacyclic graph, wherein each node of the directed acyclic graphrepresents an encapsulation of functionality of one or more of theplurality of resources, each edge of the directed acyclic graphrepresents a client request, and adjacent nodes of the directed acyclicgraph represent resource dependencies; means for receiving a resourcerequest indicating a resource defined by the directed acyclic graph;means for determining if the resource request is associated with atransaction; means for performing the resource request on the indicatedresource if the resource request is not associated with a transaction;and means for adding information associated with the resource requeststo a queue instead of performing the resource request on the indicatedresource if the resource request is associated with a transaction. 40.The method of claim 39, wherein the means for performing the resourcerequest on the indicated resource comprises: means for locking theindicated resource; means for initiating the resource request on theindicated resource; and means for unlocking the indicated resource inresponse to an indication of completion of the resource request.
 41. Themethod of claim 39, further comprising: means for determining if a queueexists prior to adding information associated with the resource requeststo the queue; and means for creating the queue if the queue does notexist and the resource request is associated with a transaction.
 42. Acomputer program product comprising a computer usable medium having acomputer readable program code embodied therein, said computer readableprogram code adapted to be executed to implement a method for batchingresource requests in a portable computing device having a plurality ofresources, said method comprising: instantiating a plurality of nodes,each node having at least one of the plurality of resources, theplurality of resources defined by a directed acyclic graph, wherein eachnode of the directed acyclic graph represents an encapsulation offunctionality of one or more of the plurality of resources, each edge ofthe directed acyclic graph represents a client request, and adjacentnodes of the directed acyclic graph represent resource dependencies;receiving a resource request indicating a resource defined by thedirected acyclic graph; determining if the resource request isassociated with a transaction; if the resource request is not associatedwith a transaction, performing the resource request on the indicatedresource; and if the resource request is associated with a transaction,adding information associated with the resource requests to a queueinstead of performing the resource request on the indicated resource.43. The computer program product of claim 42, wherein performing theresource request on the indicated resource comprises: locking theindicated resource; initiating the resource request on the indicatedresource; and unlocking the indicated resource in response to anindication of completion of the resource request.
 44. The computerprogram product of claim 42, wherein the method further comprises:determining if a queue exists prior to adding information associatedwith the resource requests to the queue; and creating the queue if thequeue does not exist and the resource request is associated with atransaction.